The present invention relates to a charged-particle beam drawing method for drawing the pattern of a semiconductor integrated circuit such as an LSI on a sample such as a mask or wafer at high speed and high precision and, more particularly, to a data creation method for realizing high-precision drawing using drawing pattern data prepared by compressing data, and a charged-particle beam drawing apparatus using the same.
In recent years, LSI patterns continue to shrink in feature size and increase in integration degree. For example, the integration degree of DRAMs is increasing from 64 M to 256 M, 1 G, and 4 G. The micropatterning technique is one of the most important process techniques.
An electron beam drawing apparatus, which can perform micropatterning at 0.1 xcexcm or less, is expected as an effective exposure means for forming a highly integrated LSI pattern. In drawing a desired LSI pattern using this electron beam drawing apparatus, design pattern data created by a pattern data creation tool such as a CAD used for LSI pattern design cannot be directly supplied as drawing pattern data for the electron beam drawing apparatus. For this reason, design pattern data must be converted into a data system receivable by the electron beam drawing apparatus so as to draw the data at a high speed.
An example of the electron beam drawing apparatus will be described. FIG. 9 shows the data flow (prior art) of a drawing system. In the data conversion step, design pattern data 51 stored in an external storage device such as a magnetic disk is read in the memory of a computer in data read (step 50). In data processing (step 52), a multiple-exposed region is removed, and correction processing such as proximity effect correction is done. Then, basic figure division (step 53) into a rectangle, trapezoid, triangle, and the like is executed for each unit drawing region determined by a beam deflection region. Accordingly, the design pattern data 51 is converted into drawing pattern data 55 receivable by the electron beam drawing apparatus.
In drawing data storage (step 54), the converted drawing pattern data 55 is stored in an external storage device represented by a magnetic disk.
In the data transfer step, the drawing pattern data 55 converted in the previous step is read in step 56, transferred to a buffer memory in step 57, and registered in step 58. Then, the data transfer step is complete.
In the drawing step, JOB data 61 serving as drawing schedule data of the electron beam apparatus is read in drawing condition setting (step 60). In stripe data read (step 62), drawing pattern data of one stripe to be drawn by one stage scanning is read out from the buffer memory in step 58. The drawing pattern data made up of basic figures undergoes bitmapping processing (step 63). The bitmap data is transferred to a pattern memory in step 64, and output to a beam blanker serving as a beam-ON/OFF means in step 65. Then, an electron beams is ON/OFF-controlled to draw a pattern (step 66). After one stripe is drawn, the drawing step restarts from stripe data read (step 62) for drawing the next stripe. This is repeated to complete drawing of all chips placed on a wafer.
FIG. 10 is a block diagram showing an electron beam drawing apparatus for drawing a pattern in accordance with data flow (prior art) of the above drawing system. The electron beam drawing apparatus is roughly constituted by an electron beam drawing apparatus main body 280 and a drawing control system 290. The electron beam drawing apparatus main body 280 is comprised of an electron gun 201, convergent lens 202, reduction lens 203, deflector 204, blanker 205, and stage 207. An electron beam EB emitted by the electron gun 201 is converged into 0.1 xcexcm or less via the convergent lens 202 and reduction lens 203 to irradiate a wafer 208 on the stage. The electron beam EB is adjusted in position by the deflector 204 (made up of two, a main deflector 204-1 and a sub-deflector 204-2), and ON/OFF-controlled by the blanker 205.
An electron beam EB emitted by the electron gun 201 is converged into 0.1 xcexcm or less via the convergent lens 202 and reduction lens 203 to irradiate a wafer 208 on the stage. The electron beam EB is adjusted in position by the deflector 204 (made up of two, main deflector 204-1 and sub-deflector 204-2), and ON/OFF-controlled by the blanker 205.
In the drawing control system 290, drawing pattern data 224 stored in an external storage device 210 such as a magnetic disk is transferred via a CPU 212 to an internal buffer memory 214 of a drawing data processing unit 219 on the basis of settings from a console 211. The data format of the drawing pattern data 224 is a basic figure such as a rectangle, trapezoid, triangle, or the like, which is obtained by dividing design pattern data into figures. The drawing pattern data 224 is subjected in figure calculation processing 217 to calculation processing of converting data of one stripe to be drawn by one stage scanning into bitmap data. Then, the bitmap data is transferred to a pattern memory 218.
After the bitmap data is transferred to a blanker control unit 220, the electron beam EB is ON/OFF-controlled. In synchronism with this, a deflector control unit 222 settles the beam position, and a stage control unit 223 controls the stage position. A series of drawing operations is performed.
FIGS. 11A to 11C show a drawing method when the deflector 204 shown in FIG. 10 is made up of the two, main deflector 204-1 and sub-deflector 204-2. The stage reciprocally scans in a direction (X) perpendicular to the beam deflection direction (Y) of the electron beam EB by the main deflector 204-1, thereby drawing a pattern on all the regions of chips 251 arrayed on the wafer 208. Within the region of a main field 252 scanned by the main deflector 204-1, the sub-deflector 204-2 deflects the electron beam EB to draw a pattern in the region of a smaller subfield 254. The region where the electron beam EB is deflected in the subfield 254 is defined as a basic drawing region, which is reflected on data of basic figure division in creating drawing pattern data from design pattern data in the data conversion step.
As described above, in the conventional electron beam drawing apparatus, design pattern data is defined by a figure system comprised of receivable basic figures (rectangle, trapezoid, triangle, and the like). Further, the design pattern data is defined by a data system obtained by region division for each unit drawing region which depends on the drawing method of the electron beam drawing apparatus. In this manner, drawing pattern data is created to draw a pattern.
However, this method suffers the following problem.
More specifically, when sorting processing (data rearrangement processing in the drawing order) is executed in units of basic drawing regions while design pattern data created by the CAD is converted into drawing pattern data, the repetitive periodic structure of the pattern of the design pattern data becomes different in size from the unit drawing region of the electron beam drawing apparatus, and becomes different in size from the main field. If the design pattern data is simply divided in units of unit drawing regions/main field regions, the repetitive periodic structure is inhibited. The data must be mapped into many independent divided patterns, which makes it difficult to compress drawing pattern data. For this reason, the pattern regularity defined by the design pattern data is destroyed to increase the data amount and prolong the data conversion time.
Also, in the data transfer step before the start of drawing, a time required to transfer drawing pattern data obtained by data conversion from an external storage device represented by a magnetic disk to a buffer memory unit is prolonged. In the drawing step, a long time is spent on bitmapping drawing pattern data made up of basic figures.
From this, the time required for a series of data processes decreases the throughput of the electron beam drawing apparatus.
Recently, there is proposed a method of drawing a pattern by ON/OFF-controlling a plurality of electron beams in parallel with each other using multi-beams. A plurality of electron beams are arranged in m rowsxc3x97n columns (m and n are integers of 1 or more), and each electron beam draws a pattern in a basic drawing region, thereby drawing a two-dimensional pattern. This high-speed drawing method also suffers the same problem because the periodicity of design pattern data does not coincide with that of basic drawing regions arranged in m rowsxc3x97n columns. This inhibits increasing the speed of the electron beam drawing apparatus.
In this situation, compression of drawing pattern data is limited in the current data conversion step. Moreover, the speeds of the data conversion and drawing steps cannot be increased. The above-mentioned problem decreases the availability of the electron beam drawing apparatus, and decreases the productivity of LSIs. This may pose a serious problem on increasing the reliability of an LSI pattern drawn by the electron beam drawing apparatus and the availability of the apparatus along with shrinkage in LSI feature size and increase in integration degree.
The present invention has been proposed to solve the conventional problems, and has as its object to provide a drawing pattern data creation method capable of increasing the compression efficiency of drawing pattern data, increasing the speed of the drawing step, and thus increasing the throughput even when the periodicity of design pattern data is different from the arrangement periodicity of basic drawing regions defined by the drawing method of an electron beam drawing apparatus, and an electron beam drawing apparatus using the same.
To achieve the above object, a data creation method and a charged-particle beam drawing apparatus using the same according to the present invention comprise the following steps and arrangement.
That is, a charged-particle beam drawing data creation method of supplying bit information created from design pattern data in a scanning direction of a charged-particle beam, ON/OFF-controlling the charged-particle beam to irradiate a sample surface, and exposing a two-dimensional pattern by scanning the charged-particle beam comprises the steps of:
extracting a cell pattern as one unit of a periodic structure from design pattern data having a periodic structure, and registering the cell pattern,
creating arrangement data to be rearranged in a basic drawing region defined by a charged-particle beam exposure apparatus using the cell pattern, and registering the arrangement data, and
cutting out data from the cell pattern in accordance with information of the arrangement data, and creating data of the basic drawing region.
According to one preferable aspect of the present invention, in the charged-particle beam drawing data creation method, the basic drawing region includes all or some of regions of a plurality of cell patterns.
According to another preferable aspect of the present invention, in the charged-particle beam drawing data creation method, the cell pattern is not smaller in size than the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing data creation method, the cell pattern is smaller in size than the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing data creation method, the basic drawing region includes at least some of cell patterns not smaller in size than the basic drawing region and some of cell patterns smaller in size than the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing data creation method, the cell pattern is not less than twice the size of the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing data creation method, the cell pattern is formed from bitmap data.
A charged-particle beam exposure apparatus for supplying bit information created from design pattern data in a scanning direction of a charged-particle beam, ON/OFF-controlling the charged-particle beam to irradiate a sample surface, and exposing a two-dimensional pattern by scanning the charged-particle beam comprises:
means for extracting a cell pattern as one unit of a periodic structure from design pattern data having a periodic structure, and registering the cell pattern,
means for creating arrangement data to be rearranged in a basic drawing region defined by the charged-particle beam exposure apparatus using the cell pattern, and registering the arrangement data, and
means for cutting out data from the cell pattern in accordance with information of the arrangement data, and creating data of the basic drawing region.
According to one preferable aspect of the present invention, in the charged-particle beam drawing apparatus, the basic drawing region includes all or some of the regions of a plurality of cell patterns.
According to another preferable aspect of the present invention, in the charged-particle beam drawing apparatus, the cell pattern is not smaller in size than the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing apparatus, the cell pattern is smaller in size than the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing apparatus, the cell pattern is not less than twice the size of the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing apparatus, the cell pattern is not less than twice in size the basic drawing region.
According to still another preferable aspect of the present invention, in the charged-particle beam drawing apparatus, the cell pattern is formed from bitmap data.
According to still another preferable aspect of the present invention, the charged-particle beam drawing apparatus further comprises a plurality of charged-particle beams and a plurality of beam-ON/OFF means arranged in m rowsxc3x97n columns,
wherein in a drawing method of drawing patterns in parallel with each other in respective basic drawing regions by the charged-particle beams,
bitmap drawing data are supplied in parallel with each other to the respective beam-ON/OFF means in the scanning direction of the charged-particle beam, and
the plurality of charged-particle beams are controlled to irradiate a sample surface, thereby drawing a two-dimensional pattern.
The above steps and arrangement can increase the compression efficiency of drawing pattern data, can increase the speed of the drawing step, and thus can increase the throughput even when the periodicity of design pattern data is different from the arrangement periodicity of basic drawing regions defined by the drawing method of the electron beam drawing apparatus.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.